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Analysis of the Abscopal Effect with Anti-PD1 Therapy in Patients with Metastatic Solid Tumors
Gomes, J.R., Schmerling, R.A., Haddad, C.K., (...), Zanuncio, P., Buzaid, A.C.
Journal of Immunotherapy, 2016 Nov/Dec;39(9):367-372
Combination of Radiotherapy with Anti-Programmed Death Cell 1 Therapy: Analysis ofthe Abscopal Effect
One of the rare phenomena of radiation therapy in cancer is regression of metastatic tumoursuntreated by localized radiation therapy which is known as the abscopal effect. With the recentfocus on combination of radiation and systemic novel drug in non-small cell lung cancer (NSCLC),it is interesting to evaluate whether there is an increased probability of abscopal effect with thisnew approach.
Hence a retrospective analysis was performed where the abscopal effects of radiation combinedwith anti-programmed death cell 1 (anti-PD1) was assessed in patients with melanoma, non-smallcell lung cancer (NSCLC) and renal cancer. The abscopal effect was defined as a positive responseto therapy outside the irradiated area while being treated with anti-PD1 drugs.
The analysis included 16 patients of which 12 had melanoma, two NSCLC and two renal cellcarcinoma, all in metastatic condition. All patients were being treated with anti-PD1 drugs andhad a disease progression at a median time of 3 months. These patients were administered localizedradiation therapy for lungs, lymph nodes and bones at a median dose of 24 Gy (range: 1-40 Gy) in3 fractions (range: 1-10 fractions). Only three patients with melanoma demonstrated an abscopaleffect at the rate of 18.7%. Notably one patient showed complete response to therapy for a periodof 6 months.
To conclude, the abscopal effect was observed in 25% melanoma patients treated with anti-PD1and radiation and in none of the patients with NSCLC and renal cancer